DNA methylation is a post replicative chemical modification of DNA. Different cancers can be stratified by their abnormal DNA methylation profiles (degree of global or specific DNA methylation) and the hypermethylation of specific genes can be associated with the prognosis for gastric, lung, esophageal, pancreatic, and colon cancer. DNA methylation patterns can also be used to predict response or resistance to therapy in glioma and melanoma. Azacitidine and decitabine are two FDA approved hypomethylating agents (HMAs) that exert their therapeutic effect by inhibiting DNA methylation levels.
Lyophilization, often referred to as freeze drying, is a method of dehydration in which a solvent-containing substrate is frozen and then subjected to a vacuum so that the solvent is removed by sublimation, i.e. direct conversion from the solid frozen state into the gaseous state.